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        <div>
            <div><h4 class="title">
                <a name="asio.reference.co_spawn.overload5"></a><a class="link" href="overload5.html"
                                                                   title="co_spawn (5 of 6 overloads)">co_spawn (5 of 6
                overloads)</a>
            </h4></div>
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    </div>
    <p>
        Spawn a new coroutined-based thread of execution.
    </p>
    <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <a class="link" href="../Executor1.html" title="Executor requirements">Executor</a><span
                class="special">,</span>
    <span class="keyword">typename</span> <span class="identifier">F</span><span class="special">,</span>
    <span class="keyword">typename</span> <span class="identifier">CompletionToken</span> <span class="special">=</span> <a
                class="link"
                href="../asynchronous_operations.html#asio.reference.asynchronous_operations.default_completion_tokens"><span
                class="emphasis"><em>DEFAULT</em></span></a><span class="special">&gt;</span>
<a class="link"
   href="../asynchronous_operations.html#asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span
        class="emphasis"><em>DEDUCED</em></span></a> <span class="identifier">co_spawn</span><span
                class="special">(</span>
    <span class="keyword">const</span> <span class="identifier">Executor</span> <span class="special">&amp;</span> <span
                class="identifier">ex</span><span class="special">,</span>
    <span class="identifier">F</span> <span class="special">&amp;&amp;</span> <span class="identifier">f</span><span
                class="special">,</span>
    <span class="identifier">CompletionToken</span> <span class="special">&amp;&amp;</span> <span class="identifier">token</span> <span
                class="special">=</span> <a class="link"
                                            href="../asynchronous_operations.html#asio.reference.asynchronous_operations.default_completion_tokens"><span
                class="emphasis"><em>DEFAULT</em></span></a><span class="special">,</span>
    <span class="keyword">typename</span> <span class="identifier">constraint</span><span
                class="special">&lt;</span> <span class="identifier">is_executor</span><span class="special">&lt;</span> <span
                class="identifier">Executor</span> <span class="special">&gt;::</span><span
                class="identifier">value</span><span class="special">||</span><span
                class="identifier">execution</span><span class="special">::</span><span
                class="identifier">is_executor</span><span class="special">&lt;</span> <span
                class="identifier">Executor</span> <span class="special">&gt;::</span><span
                class="identifier">value</span> <span class="special">&gt;::</span><span class="identifier">type</span>  <span
                class="special">=</span> <span class="number">0</span><span class="special">);</span>
</pre>
    <h6>
        <a name="asio.reference.co_spawn.overload5.h0"></a>
        <span><a name="asio.reference.co_spawn.overload5.parameters"></a></span><a class="link"
                                                                                   href="overload5.html#asio.reference.co_spawn.overload5.parameters">Parameters</a>
    </h6>
    <div class="variablelist">
        <p class="title"><b></b></p>
        <dl>
            <dt><span class="term">ex</span></dt>
            <dd><p>
                The executor that will be used to schedule the new thread of execution.
            </p></dd>
            <dt><span class="term">f</span></dt>
            <dd><p>
                A nullary function object with a return type of the form <code class="computeroutput"><span
                    class="identifier">asio</span><span class="special">::</span><span
                    class="identifier">awaitable</span><span class="special">&lt;</span><span
                    class="identifier">R</span><span class="special">,</span><span class="identifier">E</span><span
                    class="special">&gt;</span></code>
                that will be used as the coroutine's entry point.
            </p></dd>
            <dt><span class="term">token</span></dt>
            <dd><p>
                The <a class="link" href="../../overview/model/completion_tokens.html" title="Completion Tokens">completion
                token</a> that will handle the notification that the thread of
                execution has completed. If <code class="computeroutput"><span class="identifier">R</span></code>
                is <code class="computeroutput"><span class="keyword">void</span></code>, the function
                signature of the completion handler must be:
            </p></dd>
        </dl>
    </div>
    <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span
            class="special">(</span><span class="identifier">std</span><span class="special">::</span><span
            class="identifier">exception_ptr</span><span class="special">);</span>
</pre>
    <p>
        Otherwise, the function signature of the completion handler must be:
    </p>
    <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span
            class="special">(</span><span class="identifier">std</span><span class="special">::</span><span
            class="identifier">exception_ptr</span><span class="special">,</span> <span class="identifier">R</span><span
            class="special">);</span>
</pre>
    <h6>
        <a name="asio.reference.co_spawn.overload5.h1"></a>
        <span><a name="asio.reference.co_spawn.overload5.completion_signature"></a></span><a class="link"
                                                                                             href="overload5.html#asio.reference.co_spawn.overload5.completion_signature">Completion
        Signature</a>
    </h6>
    <pre class="programlisting"><span class="keyword">void</span><span class="special">(</span><span class="identifier">std</span><span
            class="special">::</span><span class="identifier">exception_ptr</span><span class="special">,</span> <span
            class="identifier">R</span><span class="special">)</span>
</pre>
    <p>
        where <code class="computeroutput"><span class="identifier">R</span></code> is the first template
        argument to the <code class="computeroutput"><span class="identifier">awaitable</span></code>
        returned by the supplied function object <code class="computeroutput"><span class="identifier">F</span><span
            class="special">:</span></code>
    </p>
    <pre class="programlisting"><span class="identifier">asio</span><span class="special">::</span><span
            class="identifier">awaitable</span><span class="special">&lt;</span><span class="identifier">R</span><span
            class="special">,</span> <span class="identifier">AwaitableExecutor</span><span class="special">&gt;</span> <span
            class="identifier">F</span><span class="special">()</span>
</pre>
    <h6>
        <a name="asio.reference.co_spawn.overload5.h2"></a>
        <span><a name="asio.reference.co_spawn.overload5.example"></a></span><a class="link"
                                                                                href="overload5.html#asio.reference.co_spawn.overload5.example">Example</a>
    </h6>
    <pre class="programlisting"><span class="identifier">asio</span><span class="special">::</span><span
            class="identifier">awaitable</span><span class="special">&lt;</span><span class="identifier">std</span><span
            class="special">::</span><span class="identifier">size_t</span><span class="special">&gt;</span> <span
            class="identifier">echo</span><span class="special">(</span><span class="identifier">tcp</span><span
            class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket</span><span
            class="special">)</span>
<span class="special">{</span>
  <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span
                class="identifier">bytes_transferred</span> <span class="special">=</span> <span class="number">0</span><span
                class="special">;</span>

  <span class="keyword">try</span>
  <span class="special">{</span>
    <span class="keyword">char</span> <span class="identifier">data</span><span class="special">[</span><span
                class="number">1024</span><span class="special">];</span>
    <span class="keyword">for</span> <span class="special">(;;)</span>
    <span class="special">{</span>
      <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span
                class="identifier">n</span> <span class="special">=</span> <span
                class="identifier">co_await</span> <span class="identifier">socket</span><span
                class="special">.</span><span class="identifier">async_read_some</span><span class="special">(</span>
          <span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span
                class="special">(</span><span class="identifier">data</span><span class="special">),</span> <span
                class="identifier">asio</span><span class="special">::</span><span
                class="identifier">use_awaitable</span><span class="special">);</span>

      <span class="identifier">co_await</span> <span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">async_write</span><span class="special">(</span><span
                class="identifier">socket</span><span class="special">,</span>
          <span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span
                class="special">(</span><span class="identifier">data</span><span class="special">,</span> <span
                class="identifier">n</span><span class="special">),</span> <span class="identifier">asio</span><span
                class="special">::</span><span class="identifier">use_awaitable</span><span class="special">);</span>

      <span class="identifier">bytes_transferred</span> <span class="special">+=</span> <span
                class="identifier">n</span><span class="special">;</span>
    <span class="special">}</span>
  <span class="special">}</span>
  <span class="keyword">catch</span> <span class="special">(</span><span class="keyword">const</span> <span
                class="identifier">std</span><span class="special">::</span><span
                class="identifier">exception</span><span class="special">&amp;)</span>
  <span class="special">{</span>
  <span class="special">}</span>

  <span class="identifier">co_return</span> <span class="identifier">bytes_transferred</span><span
                class="special">;</span>
<span class="special">}</span>

<span class="comment">// ...</span>

<span class="identifier">asio</span><span class="special">::</span><span class="identifier">co_spawn</span><span
                class="special">(</span><span class="identifier">my_executor</span><span class="special">,</span>
  <span class="special">[</span><span class="identifier">socket</span> <span class="special">=</span> <span
                class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span
                class="special">(</span><span class="identifier">my_tcp_socket</span><span
                class="special">)]()</span> <span class="keyword">mutable</span>
    <span class="special">-&gt;</span> <span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">awaitable</span><span class="special">&lt;</span><span
                class="keyword">void</span><span class="special">&gt;</span>
  <span class="special">{</span>
    <span class="keyword">try</span>
    <span class="special">{</span>
      <span class="keyword">char</span> <span class="identifier">data</span><span class="special">[</span><span
                class="number">1024</span><span class="special">];</span>
      <span class="keyword">for</span> <span class="special">(;;)</span>
      <span class="special">{</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span
                class="identifier">n</span> <span class="special">=</span> <span
                class="identifier">co_await</span> <span class="identifier">socket</span><span
                class="special">.</span><span class="identifier">async_read_some</span><span class="special">(</span>
            <span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span
                class="special">),</span> <span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">use_awaitable</span><span class="special">);</span>

        <span class="identifier">co_await</span> <span class="identifier">asio</span><span
                class="special">::</span><span class="identifier">async_write</span><span class="special">(</span><span
                class="identifier">socket</span><span class="special">,</span>
            <span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span
                class="special">,</span> <span class="identifier">n</span><span class="special">),</span> <span
                class="identifier">asio</span><span class="special">::</span><span
                class="identifier">use_awaitable</span><span class="special">);</span>
      <span class="special">}</span>
    <span class="special">}</span>
    <span class="keyword">catch</span> <span class="special">(</span><span class="keyword">const</span> <span
                class="identifier">std</span><span class="special">::</span><span
                class="identifier">exception</span><span class="special">&amp;</span> <span
                class="identifier">e</span><span class="special">)</span>
    <span class="special">{</span>
      <span class="identifier">std</span><span class="special">::</span><span class="identifier">cerr</span> <span
                class="special">&lt;&lt;</span> <span class="string">"Exception: "</span> <span
                class="special">&lt;&lt;</span> <span class="identifier">e</span><span class="special">.</span><span
                class="identifier">what</span><span class="special">()</span> <span
                class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
    <span class="special">}</span>
  <span class="special">},</span> <span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">detached</span><span class="special">);</span>
</pre>
    <h6>
        <a name="asio.reference.co_spawn.overload5.h3"></a>
        <span><a name="asio.reference.co_spawn.overload5.per_operation_cancellation"></a></span><a class="link"
                                                                                                   href="overload5.html#asio.reference.co_spawn.overload5.per_operation_cancellation">Per-Operation
        Cancellation</a>
    </h6>
    <p>
        The new thread of execution is created with a cancellation state that supports
        <code class="computeroutput"><span class="identifier">cancellation_type</span><span
                class="special">::</span><span class="identifier">terminal</span></code> values only. To change the
        cancellation
        state, call <a class="link" href="../this_coro__reset_cancellation_state.html"
                       title="this_coro::reset_cancellation_state"><code class="computeroutput"><span
            class="identifier">this_coro</span><span class="special">::</span><span class="identifier">reset_cancellation_state</span></code></a>.
    </p>
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                file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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